Major Histocompatibility Complex I Mediates Immunological Tolerance of the Trophoblast during Pregnancy and May Mediate Rejection during Parturition

Figure 4

Hypothetical mechanism explaining why expression of classical MHC I during gestation is needed for fetal membranes rejection during parturition. In cows and horses trophoblast has no access to maternal blood (in contrast to humans). In these species trophoblast expresses classical MHC I with paternal antigens during pregnancy. This expression “teaches” maternal memory cells, which recognize paternal (foreign) antigen. If during parturition fetal membranes reexpress classical MHC I with paternal antigens they will stimulate booster effect from maternal memory cells and lead to fetal membranes rejection.